RDMA/mlx5: Initialize SRQ tables on mlx5_ib

Transfer initialization and cleanup from mlx5_priv struct of
mlx5_core_dev to be part of mlx5_ib_dev. This completes removal
of SRQ from mlx5_core.

Reviewed-by: Mark Bloch <markb@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>